i took my header off to get it welded, and had to take it off all the way back to the cat, and i got the idea to take off the cat and knock out the material inside it and throw it back on. is this a bad idea? could this cause any problems?

 

runs like a straight pipe - a bit louder and less restriction.
Had to do this a couple times myself when CAT was breaking down and clogging.

 

so i wont lose horsepower or anything? idk my brother did it to his mustang but he said if i do it ill lose horsepower or some **** idk if hes just being a dick or what

 

I swear to god, if someone in here starts yammering about backpressure....

 

haha thats what my bro was saying but he doesnt no **** about honda's

 

dood ur back pressure sux jajaja, jk i actually went to mills fleet farm and replaced my cat with a cherrybomb.

 

so is it better to run it with the cat, or with the empty cat? as long as its not bad for it, and it has the same hp or more im going to go for it i guess.

 

i know on the S2000 if you hallow the cat out it has shown powerless on the dyno

i would think going from a the header to a big opening (hallowed Cat) to the smaller exhaust would cause a flow problem.

 

is this true? anyone else have anything to say about this?

 

I would replace the section with same ID straight pipe instead of hollowing the cat. Hollowing the cat will create a low velocity problem and decrease power.

 

oh well around here i believe inspection they look too see if it has a cat on older models, so it would pass with a hollowed cat but not without one.

 

WHat, they only inspect not sniff your exhaust?

 

http://www.autozone.com/autozone/cat...&parentId=61-0

 

Don't know down south but in canada Catalytics became mandatory after 1991. The law says if your car came with one prior to this it by law has to have one, and anything after 91 requires it.

My 1990 civic shop manual shows they came both with and without catalytic converters. I didn't have one on my car just a straight pipe. It's better to put on a straight pipe then to gut a cat. You cut gut it and weld a straight pipe inside of the cat.

 

i guess so, cuz my bro knocked out his cat in his 91 mustang about a year ago, and his passes, and what was the point of the link?

 

i would do that but i dont have a welder and dont feel like bothering my friends dad again haha

 

My exhaust was more raspy with a hollowed cat (b16, sk2 exhaust). I installed a high flow cat and it 100% better, no raspy popping exhaust.

 

yea i just looked it up on youtube and they sounds pretty bad with a hollow cat, i might just get a high flow

 

Depends on the cat. If its old and crappy, bang that **** out, or better yet buy aftermarket. If its aftermarket and in good shape, leave it. Honda tuning used a b16 crx to test some theorys. And from the old stock cat to the aftermarket they gained like 3.5whp (new one was larger). then they put straight pipe on inplace of the new cat and it only gained like 1 more whp. So do what you think is best. My .02 is to use a decent aftermarket.

 

well, if u cat is not fuctioning anymore and clogging then yes gutting it will increase what u lost in the beginning.
but so far increasing hp will it hollow. if there's some be little. u not going to lose power by doing that, u gain some but more like at peak.

 

English dude, and yes you can loose power with that empty chamber your changing the flow of exhaust.

 

If there is any power difference I seriously doubt you are going to notice it.
Figuring 'maybe' 3 hp.
Obviously this isn't a pro drag car so who cares.

 

i just want to know if it can cause any problems ?

 

no.

 

I would much rather remove the cat and buy or make a straight piece. I read your thread and I know you don't worry about smog issues but its good to have a Cat on the shelf just incase.
But its your car. Knock the honeycomb out of it!

Just dont breath that sht in! It is toxic!